Improvement in valve-gear for steam-engines



E. BROWN. VALVE GEAR FOR STEAM ENGINES.

NORRIS PETERS on wuo'ro-umoq WASNINGTON. n. 0..

UNITED STATES PATENT OFFICE.

EDWARD BROWN, or PHILADELPHIA, PENNQ SY LvA'NiAL IMPROVEMENT IN VALVE-GEAR Foa STEAMEENGII'N'E'S.

Specification forming part of Letters Patent No. 44,071, dated September-6, 1864.

To all whom it may concern:

Be it known that I, EDWARD BROWN, of Phi1ade1phia,count y of Philadelphia, and State of Pennsylvania, have invented a new and Improved Modeof Operating the Slide-Valves of bteamEngines; and I do hereby declare that the following is a full, clear, and exact de-- The nature of my invention consists in op erating the slide-valve of a steam-engine by meansof a grooved-disk fitted on the main Shaft of the engine and capable of being fixed in any required position or angle, and a common eccentric, the rods from which eccentric and disk are connected to a link or lever which works the valve-stem of the engine. The commonest'kind of steam-engine is the three-port slide-valve, the valve of which is generally operated by means of an eccentric or by two eccentrics connected by a slotted link. Themotion communicated by this means is very defective in cutting off the steam at an early point of the stroke. In fact, it will not out 011' much earlier than half stroke without giving a very small port. The motion atthe point of cut oft isvery slow,.and the compression and exhaust are too early, thus neutralizing the advantage of cutting off the steam short.

By my mode-of operating the slide-valve the port is larger, the cut-off much more rapid,

-(an essential point,) while the lead-points of compression and exhaust remain the same when cutting off at one-sixth'as atthree-qua-rters of the stroke.

. I will now describe the parts:

In Fig. 1, D is the main shaft of the engine A is the grooved disk. It is bored to fit the main shaft of the engine. B-is a flange fitted and keyed faston shaft D, and to which the diskA is bolted by the bolt 0 in any position that may be required. This flange B has a curved slot in it, aslshown at f, Fig. 5, in which the bolt e works laterally when the disk A is moved round the shaft;

0 is a common eccentric keyed fast on the; shaft D, and connected to one en.d,.S, of lever B by means of a rod, Q. '13 represents the crank of the engine, and g the crank-pin. The disk A has a groove cast in its side, as shown in Fig. 3. The groove in this disk is formed by two curves, H and I, concentric with the center of shaft 1), but at different distances fromthe center. These curves are joined by the grooves Jand K, forming inclined planes. In this groove runs a roller, L. (See Fig. 4). It turns on a pin, n, fixed in the carrying-arm m. This arm in vibratesoii the pin 0, fixed to the framing vofthe engine. To it is also fixed, by a pin, 10, the'connecting-arm Q, which is attached at its opposite end to one end, S, of the lever B, which said lever R is connected at its center" 0' to the valvestem T.

In Fig. 2 the diagram 20 c m 3 shows the position of the crankin relation to that of the valve Z, at the point of cnt-oifviz., four and a half inches out of a twelve inch stroke. The circle re yrepresents the path of the crank-pin, and the straight line 20 e, that of thepiston; the figures 1 2 3, &c.,.0n the line we, which the piston maybe supposed to reachsuceessively, at the same time that the crank-pin 9 reaches the points 1 2 3, 850., on the circle a. The crank travels in the direction of arrow d. The ports a and a.llead to opposite ends of the cylinder.

The operation of my valve-motion is as-follow's: The crank being placed on its dead- .cente'r 0, Fig. 2, the valve Z will. be just it'dmitting steam atthe port a. .The eccentric O iskeyed fast on the shaft D at about 011011 111".

dred and twenty degrees in advance of the crank. As the crank moves to wardposition F, the valve Z is opened by the eccentric, and ad mits steam to the cylinder. The disk A is fixed to the flange B in such a'position or angle so that the inclined part K of the groove-strikes the roller L and communicates its motion to the valve-stem T just at the time it is wanted to'cut off the steam, which will generally be from one-third to one-half of the stroke. The eccentric at this time is near the end of its throw, and consequently giving very littlc motion to the valve Z. -The'action of the in' cline K, coming against the rollef L 'at this time, gives a very rapid motion to the valve,

half a revolution, when the inclineJ comes into operation with the roller L and again cuts oft steam at the return-stroke of the piston. Thus the valve Z receivesvits motion from the eccentric 0, except when it is near the extremity of each stroke, and then the I inclines J and K come into operation and perform the cut-off.

By turning the disk A forward or backward on the shaft D and securing it fast to flange B, the inclines J and K are brought so much earlier or later in contact with roller L, thus shortening-or lengthening the period of cuting the disk A upon the shaft, the point of.

eut-ofi' may ,be altered by raising or lowering the roller L in-the groove H I by means of a lever, G, as shown in Fig. 6, and if the guyernor of the engine be attached to handle C the cut-oft is then variable by the governor. A three-cornered cam, as shown, Fig. 7 will partiallyanswer the same as disk A; but its motion in cutting off steam is not so rapid as disk A. This valve-motion may be applied to the valve-stem of three-port slide-valves, plate .or piston valves, or two-port slide-valves .at

each end of the cylinder, or balanced-slidevalves.

- I do not claimthe use of a single eccentric and cam connnected by rods to a link or lever for operating the slide-valve but What I claim as my invention, and desire to secure by. Letters Patent, is-

' 1. Operating the slide-valve .of a steamengine by means of a single eccentric, G, and a cam or grooved disk, A, when the said grooved disk is shaped as described, and the point, of cut-off varied by turning the said cam on the shaft, substantially as described.

2. The combination of the eccentric 0, disk A, flange B, roller L, arm m, rods Q Q, and lever 1t,'arranged and operating substantially as described.

1 EDWARD BROWN. Witnesses:

PARK MCFARLAND, J r., PARK MOFARLAND. 

